Categories
WW2 Czechoslovak Prototypes WW2 Yugoslavian Armor

Škoda Š-I-j

Czechoslovakia/Yugoslavia (1938)
Tankette – 1 built

As the Yugoslav Royal Army was in a search of new armored equipment, the Czechoslovak Škoda company was more than willing to offer its armored vehicles products. During the thirties, a few tankettes were presented to the Yugoslav Royal Army but performed poorly on testing so a new vehicle was requested. The following Š-I-D tankette achieved some success and eight were bought, but even this vehicle was deemed insufficient and future improvements were requested. This would lead to the development of the Š-I-j, which was presented to the Yugoslav Royal Army but for unknown reasons was never adopted.

History

In the early 1930s, the Yugoslav Royal Army began a process of reforming and reinforcing with additional equipment and armor for its two cavalry divisions. Each cavalry division consisted of two to three cavalry brigades with two regiments, one artillery squadron, a cycling battalion and other supporting units. It was planned to attach a motorized regiment to each division, supported with armor like light tanks or tankettes.

From the start, there was an issue as to where to acquire this new equipment from. While France and Yugoslavia had good military cooperation, France was unwilling to sell its latest tanks, as it wanted to dispose of the older surplus models first. Through the French, Yugoslavia had at its disposal around 56 older Renault-Kegresse M-28 and FT tanks, some having been bought and some received as military aid in the 1920-30s. By April 1940, the Kingdom of Yugoslavia managed to acquire 54 relatively modern R35 light tanks from France. The Yugoslav Royal Army had even considered acquiring some Soviet tank designs, such as the T-26 or BT series. However, mostly due to political reasons, this was not possible.

Yugoslavia negotiated with Poland and Czechoslovakia about acquiring new equipment. The negotiations with Czechoslovakia were somewhat successful and delivery of only eight Škoda Š-I-D (T-32 in Yugoslav service) was agreed.

The Š-I-D (T-32 in Yugoslav service) on parade. This picture was taken in September 1940 during military exercise near the capital, Belgrade. Source: srpskioklop.paluba.info

The Š-I-D was perhaps the most modern armored vehicle in the Yugoslavian Royal Army. Its general performance, however, proved to be disappointing. While the 37 mm gun was one of the best for its time for its size, the running gear proved to be unreliable, with a poor design that needed constant repair and was easy to break. Another issue was its armor thickness, which the Yugoslav Royal Army never deemed sufficiently strong and required to be improved. For these reasons, the Yugoslav Royal Army officials demanded from Škoda a new tankette with improved running gear, armor and main weapon. Škoda developed a much improved Š-I-j tankette. The prototype, without the gun, was completed in May 1938.

Name

The Š-I-j designation is an abbreviation, with ‘Š’ standing for the manufacturer, Škoda, ‘I’ (Roman number for 1) represents the vehicle category (category I for tankettes, category II for ‘light’ tanks and the category III for ‘medium’ tanks) and ‘j stands for ‘jugoslávský’, Yugoslav. Depending on the source, it was also marked with a capital ‘J’. But, if we take into account that the previous Š-I-D prototype was also marked with a minuscule ‘d’, we can assume that the Š-I-j designation is correct.

Škoda began changing its naming system for its production vehicles in 1940 (or in 1939 depending on the sources) and this included the Š-I-j. There are some disagreements between different authors about its later designation. According to B. Nadoveza and N. Đokić (Odbrambena privreda Kraljevine Jugoslavije), the name was changed in May 1939 to T-I-D, where the capital ‘D’ stands for Diesel. Author D. Predoević (Oklopna vozila i oklopne postrojbe u drugom svjetskom ratu u Hrvatskoj), mentioned that the name was changed to T-3D. To complicate the matter more, authors H. C. Doyle and C. K. Kliment (Czechoslovak armored fighting vehicles 1918-1945) state that the T-3D designation was used for the previously built Š-I-D tankette.

Technical Characteristics

The new Š-I-j tankette had many visual similarities with the previous built Š-I-D. The most obvious change was the redesigned and improved suspension, which had proved to be highly problematic on the previous version. It consisted of two pairs of larger road wheels (on each side), suspended by leaf-spring units. There were two front drive sprockets, two rear idlers and eight return rollers in total (with four on each side).

Drawings of the Š-I-j tankette. Source: www.palba.cz

The vehicle was equipped with (sources do not give us a precise type or name) a 3.77 liter diesel engine giving 44 kW (59 hp)@2200 rpm. The vehicle’s maximum speed was 31 km/h, but the cross-country performance is unknown. While tested with the Yugoslav Royal Army, the operational range was listed as 6 hours not in usual km.

The main armament was the Škoda A9J 47 mm gun with 42 rounds of ammunition. The gun could elevate between -10° to +25° and traverse 15° on both sides. The secondary weapon was a ZB vz.30J machine gun with 1000 rounds of ammunition.

Front view of the Š-I-j tankette. The 47 mm main gun and the machine gun next to it can be observed. The running gear was also improved, which had proved to be highly problematic on the previous version. Source: forum.warthunder.com

The superstructure consists of a simple rectangular armored casemate with a commander’s cupola on top. The armor plates were held in place with rivets. The front armor thickness was 30 mm, the sides 15 mm and the rear was 12 mm thick.

View of the rear side and the engine compartment of the Š-I-j. Source: forum.warthunder.com

The Š-I-j had two crew members: the driver who also used the machine gun, and the commander, who was at the same time the gunner and loader of the main gun. This was far from ideal, but for tankette standards of the era, it was completely normal. To gain access to their battle positions, the commander entered through the command cupola and the driver through the hatch next to it. The crew could observe the surroundings through two larger observation hatches in front, with an additional smaller one located on the driver side. For the commander, there was no need for a side observation hatch, as he had the cupola for all-around view of the surroundings.

Fate

The Š-I-j prototype was presented to a Yugoslav military delegation during March 1939. After examining the vehicle, the delegation had shown interest in the potential purchase of some 108 vehicles. By the end of 1939, the sole prototype was transported to the Kingdom of Yugoslavia for future examination. It is not clear what happened during the examination but no production orders were placed by the Yugoslav Royal Army. Possible reasons for this were that it was either deemed unsatisfactory or that more modifications were required, but the sources are not clear on the matter. It is also possible that the Yugoslav army officials simply lost interest in tankettes and wanted a ‘proper’ tank. In either case, the vehicle was returned to Škoda, where it was taken over by the Germans. Its final fate is unknown, but it can be assumed that it was probably scrapped during the war

Conclusion

While the new Š-I-j had many improvements regarding the armor, the armament, the running gear and the engine, for unknown reasons, it was never adopted by the Yugoslav Royal Army. Had it been put in service it may have been one of the best such very light vehicles in the world mainly due to its armor and armament, as most other similar vehicles were only lightly armored and armed with only machine guns.



Illustration of the Škoda Š-I-j produced by Brian Gaydos, funded by our Patreon Campaign

Specifications

Dimensions (L-W-H) 3.58 x 2.05 x 1.8 m
Total weight, battle ready 5.8 tons
Crew 2 (commander, driver)
Propulsion Unknown diesel type with 44 kW 2200 rpm, 3.77 liter
Speed 31 km/h
Armament 47 mm A-9J Gun
7.92 mm Vz.30J Machine Gun
.
Armor front plate 30 mm, sides 15 mm, rear 12 mm, floor 20 mm
Total Production 1

Sources

D. Babac (2008), Elitni vidovi jugoslovenske vojske u Aprilskom ratu. Evoluta
B. Nadoveza and N. Đokić (2014), Odbrambena privreda Kraljevine Jugoslavije,
B. B.. Dimitrijević, (2011) Borna kola Jugoslovenske vojske 1918-1941, Institut za savremenu istoriju.
Bojan B. D. and Dragan S.(2011) Oklopne jedinice na Jugoslovenskom ratištu 1941-1945, Institut za savremenu istoriju.
H.C.Doyle and C.K.Kliment (1979), Czechoslovak armored fighting vehicles 1918-1945, Argus Books Ltd.
D. Predoević (2008) Oklopna vozila i oklopne postrojbe u drugom svjetskom ratu u Hrvatskoj, Digital Point Tiskara
srpskioklop.paluba.info
www.palba.cz

Categories
WW2 Czechoslovak Prototypes WW2 German prototypes

Panzerspähwagen II Ausführung Škoda

Germany/Protectorate of Bohemia and Moravia (1940) Light Tank – 4 Prototypes Built

On 15 September 1939, the German Heereswaffenamt (Army Weapons Office – HwaA) issued new specifications for a fast, more heavily armored scout reconnaissance tank with 30 mm front armor, a 2 cm or 3.7 cm main gun and a top speed of 50 km/h. These were originally sent to the German firm MAN but, on 31 July 1940, they were also sent to two other companies, Škoda and BMM (the former Czechoslovak CKD).
The prototype Panzer T-15 light tank looks like an improved Panzer II tank but there were many differences. Its factory designation was the Škoda T-15. The first two prototypes were only built in mild structural steel.

The Panzer Späh Wagen II Ausführung Škoda, previously designated the Škoda T-15. Photo: Bundesarchiv

Name

A German Wa Prüf 6 (the German design office for armored vehicles and motorized equipment under the Heereswaffenamt – Army Ordnance Department) document dated 5 March 1942 shows the factory name Škoda T-15 being scratched through and the name Panzerspähwagen II Ausführung Skoda (Armored Scout Car II version Škoda – Pz.Sp.Wg II Ausf.Skoda) written in its place.

German Wa.Prüf. 6 original document notes that show the change of name. Photo: Herbert Ackermann

Design

The company Škoda-Werke’s T 15 design had welded armor, an improvement over the Czechoslovak built Panzer 38(t) tank’s bolted and riveted armor. The armor on the front of the turret and hull was 30 mm thick and the sides were 25 mm thick. The turret had a new curved shape with a commander’s cupola. The main gun fitted on the prototypes was the 3.7 cm Škoda A11 anti-tank gun (German designation 3.7 cm KwK 38(t) L/47). It could fire armor-piercing (AP) shells and high explosive (HE) fragmentation shells.

On 4 January 1943, the Panzerspähwagen II Ausführung Skoda prototype was shown to Hitler and senior German officers. Photo: Bundesarchiv
There was no hull machine gun. A 7.92 mm MG34 machine-gun was mounted in the turret. The driver and radio/operator were positioned at the front of the tank. Both had armored vision ports like the later Panzer II tanks.
The tank was powered by a Škoda water-cooled V8 10.8 liter 245 hp gasoline/petrol engine. The transmission had 6 forward gears and one reverse.
The suspension was different from other tanks under construction at that time. It had four pairs of large road wheels on semi-elliptic leaf springs. There were three pairs of smaller track return rollers. The drive wheel was at the rear while the idler was at the front.

Rear view of the Škoda, looking at the engine bay. The Panzerspähwagen II Ausführung Skoda prototype had four pairs of large road wheels on semi-elliptic leaf springs and three pairs of track return rollers. Photo: SOURCE
The first prototype T-15 was built in October 1941, and the second in December 1941. Tests were conducted during March and June of 1942. Further tests were completed between July and October at Kummersdorf, 25 km south of Berlin.

German Wa.Prüf. 6 original document that shows some of the vehicle’s specifications. Photo: Herbert Ackermann


Illustration of the Panzerspähwagen II Ausführung Škoda, also known as the Škoda T-15. Produced by Mr. Adrielcz, funded by our Patreon Campaign


Panzerspähwagen II T15 by adrielcz

Alterations

Alterations were made to the original design on the later prototypes. The turret shape was changed. The side armor was curved differently. An armoured driver’s vision port was fitted to the side of the chassis. The commander’s cupola was also completely redesigned. Instead of the Czech ZB.37 machine gun a German 7.92 mm MG.34 was installed. The 37mm A11 gun remained in place, but Škoda’s engineers also provided for the possibility of arming the tank with a 47 mm gun. The same Wa Prüf 6 document dated 5 March 1942 mentioned earlier showed that it was intended to mount a 5 cm PaK 39 L/60 on the production tank in a Daimler-Benz built turret.

Škoda-Werke’s redesign of the T 15 prototype wooden mockup, with improved sloping frontal hull armor, smaller turret and relocated exhaust. Photo: Yuri Pasholok

Fate

Škoda had signed a contract to build five prototypes but only built four. Construction of the fifth was stopped in early 1944 as the Panzer II Ausf.L Luchs (Lynx) was already in mass production.
Škoda completed the construction of the fifth prototype in May 1945, having restarted work in January. After the war finished, it was shown to the new Czechoslovak Army in July 1946 but no orders were placed. The Škoda tank design department used the chassis to develop different light tank projects which they called the T 15A, T 15S and T 16. They stayed as drawings. No prototypes were built.

The Pz.Sp.Wg II Ausf.Skoda prototype tank undergoing trials. There appears to be a build up of mud between the road wheels. A platform has been constructed on the right side of the turret for testing staff to have somewhere to sit as they observe what is happening. Photo: Bundesarchiv

Specifications

Dimensions (L-W-H) 4.58 x 2.17 x 2.16 meters
Total weight, battle ready 10.8 tons
Crew 4 (commander, gunner, radio operator, driver)
Propulsion Skoda T-15 8-cylinder, petrol 220 hp
Suspension semi-elliptic leaf springs
Speed (road) 50 km/h
Range 200 km
Armament 3.7 cm Skoda A11 (3.7 cm KwK 38(t) L/47), 7.92 mm MG34
Armor 8 mm – 30 mm
Total production 4 (+1 post war)

Sources

warspot.ru (Russian)
Pavel Pilar “Pruzkumne tanky Skoda T-15 a Praga TNH nA”, HPM c.3 / 2000
I.Pejcoch, O.Pejs “Obrnena technika” №6
“Hobby Historie” 2011 №10
Hilary Doyle and Thomas L. Jentz, Panzer Tracts No. 11-2: Aufklaerungspanzerwagen (Full and Half-Track Armored Reconnaissance Vehicles) H8H to Vollkettenaufklaerer 38.

Categories
WW2 Czechoslovak Prototypes WW2 German prototypes

Škoda T-25

Protectorate of Bohemia and Moravia (1942)
Medium Tank – Blueprints Only

Prior to the German occupation of Czech lands, the Škoda works was one of the largest weapon manufacturers in the world, famous for its artillery and later its armored vehicles. In the early 1930s, Škoda became involved in designing and building tankettes, followed by tanks. Many models, like the LT vz. 35 or the T-21 (built under license in Hungary), would be mass-produced, while others never passed the prototype stage. Work on a new design during wartime was slow but a few interesting projects would be developed, such as the T-25. This was an attempt to design and build a tank that would be an effective opponent of the Soviet T-34 medium tank. It would have had an innovative main gun, well-sloped armor and excellent speed. Alas, no working prototype of this vehicle was ever built (only a wooden mock-up) and it remained a paper project.

The T-25 Medium Tank. This is the second drawing of the T-25 with a recognized turret design. It is the shape by which the T-25 is generally known today. Photo: SOURCE

Škoda’s Projects

The Škoda steel works located in Pilsen founded a special armament department in 1890. In the beginning, Škoda specialized in the production of heavy fortress and naval guns, but would also in time begin designing and building field guns. After World War One and the collapse of the Austro-Hungarian Empire, the new Czech nation joined with the Slovakian nation and formed the Republic of Czechoslovakia. Škoda works survived these turbulent times and managed to preserve its place in the world as a famous weapon manufacturer. By the thirties, besides weapons production, Škoda emerged as a car manufacturer in Czechoslovakia. Škoda’s owners did not at first show any interest in the development and production of tanks. Praga (the other famous Czechoslovakian weapon manufacturer) made a contract with the Czechoslovakian military in the early 1930s for developing new tankette and tank designs. Seeing a potential new business opportunity, the Škoda owners made a decision to begin developing their own tankettes and tank designs.
During the period between 1930 and 1932, Škoda made several attempts to gain the army’s attention. By 1933, Škoda designed and produced two tankettes: the S-I (MUV-4), and the S-I-P that were shown to army officials. As Praga had already received the order for production, the army agreed only to test the Škoda tankettes without ordering them.
By 1934, Škoda abandoned the development of any future tankettes as they had proved to be ineffective as combat vehicles, and instead moved to tank designs. Škoda presented several projects to the army but it was not successful in gaining any production orders, although the S-II-a design managed to gain some attention from the army. Despite the fact that it was shown to have flaws during army testing carried out in 1935, it was still put into production under the military designation Lt. vz. 35. They received an order for 298 vehicles for the Czechoslovakian army (from 1935 to 1937) and 138 were to be exported to Romania in 1936.
By the late 1930s, Škoda suffered some setbacks in their attempts to sell vehicles abroad and with the cancellation of the S-III medium tank. By 1938, Škoda works focused on designing a new branch of medium tanks, known as the T-21, T-22 and T-23. Due to the German occupation of Czechoslovakia and the establishment of the Protectorate of Bohemia and Moravia in March 1939, the work on these models was stopped. During 1940, the Hungarian army showed great interest in the T-21 and T-22 designs, and in agreement with Škoda, a contract was signed in August 1940 for license production in Hungary.

The Name

It was common for all Czechoslovakian armored vehicle manufacturers to give their tanks and tankettes designations based on the following parameters: First would be the initial capital letter of the manufacturer’s name (for Škoda this was ’S’ or ’Š’). Then the Roman numerals I, II, or III would be used to describe the vehicle’s type (I for tankettes, II for light tanks, and III for medium tanks). Sometimes a third character would be added to denote a special purpose (like ’a’ for cavalry or ’d’ for a gun etc.). After a vehicle was accepted for operational service, the army would then give the vehicle its own designation.
The Škoda works in 1940 completely abandoned this system and introduced a new one. This new designation system was based on the capital letter ‘T’ and a number, for example, the T-24 or, the last of the series, the T-25.

History of the T-24 and T-25 Projects

During the War, the ČKD company (under German occupation the name was changed to BMM Bohmisch-Mahrische Maschinenfabrik) was very important for the German war effort. It was engaged in the production of a large number of armored vehicles based on the successful Panzer 38(t) tank.
The designers and engineers from the Škoda works were not idle during the war either and made some interesting designs. To begin with, these were on their own initiative. The largest problem for the armaments department of the Škoda works at the beginning of the war was that the German military and industry officials were not interested in expanding production of weapons to occupied countries, albeit with a few exceptions like the Panzers 35 and 38(t). During this time, Škoda weapons production was very limited. After the invasion on the Soviet Union and after suffering large losses of men and material, the Germans were forced to change this.
As nearly all German industrial capacity was directed towards supplying the Heer (German field army), the Waffen SS (more or less a Nazi army) was often left empty-handed. In 1941, Škoda presented the Waffen SS with a self-propelled-gun project based on the T-21 and armed with the 10.5 cm howitzer. A second project, the T-15, was conceived as a fast light reconnaissance tank and was also presented. Although the SS was interested in the Škoda designs, nothing came from this.
Škoda designers and engineers had the opportunity to examine some captured Soviet T-34 and KV-1 models (possibly in late 1941 or early 1942). It would not be wrong to say that they were perhaps shocked to discover how these were superior in protection, firepower, and in having larger tracks when compared to their own tanks, and even to many German tank models at that time. As a result, they immediately began working on a brand new design (it would have nothing in common with older Škoda designs) with much better armor, mobility, and sufficient firepower. They hoped that they could convince the Germans, who were desperate at that time for an armored vehicle which could effectively fight Soviet tanks. From this work, two similar designs would be born: the T-24 and the T-25 projects.
The Germans made an agreement with Škoda at the beginning of 1942 giving them permission to develop a new tank design based on several criteria. The most important conditions set by the German army were: ease of production with minimal important resources used, to be able to be produced quickly and to have a good balance of firepower, armor, and mobility. The first wooden mock-ups to be built were to be ready by the end of July 1942, and the first fully operational prototype was to be ready for testing in April 1943.
The first proposed project was submitted in February 1942 to the German weapons testing office (Waffenprüfungsamt). Known under the designation T-24, it was an 18.5-tonne medium tank armed with a 7.5 cm gun. The T-24 (and later T-25) was heavily influenced by the Soviet T-34 in regards to the sloping armor design and the forward mounted turret.
The second proposed project was known under the designation T-25, and was to be much heavier at 23 tonnes with the same caliber (but different) 7.5 cm gun. This project was proposed to the Germans in July 1942 and the necessary technical documentation was ready in August 1942. The T-25 looked more promising to the Germans as it fulfilled the request for good mobility and firepower. Due to this, the T-24 was discarded at the beginning of September 1942. The earlier built T-24 wooden mock-up was scrapped and all work on it was halted. The development of the T-25 continued until the end of the year, when, in December 1942, the German military lost all interest in it and ordered Škoda to stop any future work on this project. Škoda proposed two self-propelled designs based on the T-25 armed with 10.5 cm and a larger 15 cm howitzers, but as the whole project was abandoned, nothing came from this.

What Would it Have Looked Like?

There is enough information about the technical characteristics of the T-25 tank, but the exact appearance is somewhat unclear. The first drawing of the T-25 was dated 29th of May 1942 (under the designation Am 2029-S). What is interesting about this drawing is what seems to be a display of two different turrets placed on one hull (the T-24 and T-25 had very similar hulls but with different dimensions and armor). The smaller turret, in all likelihood, belongs to the first T-24 (it can be identified by the shorter 7.5 cm gun) while the larger one should belong to the T-25.

The first drawing (designated Am 2029-S) of the T-25 together with the seemingly smaller turret that may have belonged to the T-24. As these two had a very similar design, it is easy to mistake them for one vehicle, when in fact, they were not. Photo: SOURCE
The second drawing of the T-25 was made (possibly) in late 1942 and its turret has a completely different design. The second turret is somewhat higher, with two top metal plates instead of a single one. The front part of the first turret would most likely (it is difficult to determine exactly) be rectangular shaped, while the second would have more complicated hexagonal shape. The existence of two different turret designs may at first glance seem somewhat unusual. The explanation may lie in the fact that in May the T-25 was still at its early research and design phase, and so by the latter part of the year, some changes were necessary. For example, the gun installation demanded more space and thus the turret needed to be somewhat larger, with more space necessary for the crew to work effectively.

Technical Characteristics

Unlike the problem with the determination of the exact appearance of the T-25 tank, there is reliable information and sources concerning the technical characteristics of the Škoda T-25, from the engine used and the estimated maximum speed, armor thickness, and armament, to the number of crew. It is very important to note, however, that in the end the T-25 was only a paper project and it was never constructed and tested, so these numbers and information may have changed on a real prototype or later during production.
The T-25 suspension consisted of twelve 70 mm diameter road wheels (with six on both sides) each of which had a rubber rim. The wheels were connected in pairs, with six pairs in total (three on each side). There were two rear drive sprockets, two front idlers, and no return rollers. Some sources state that the front idlers were, in fact, drive sprockets, but this seems unlikely. Examination of the rear part (exactly at the last wheel and drive sprocket) on the drawing designated Am 2029-S of the T-25 reveals what appears to be a transmission assembly for powering the rear sprockets. The front hull design appears to have left no available space for installation of a front transmission. The suspension consisted of 12 torsion bars located beneath the floor. The tracks would be 460 mm wide with a possible ground pressure of 0.66 kg/cm².
The T-25 was planned at first to be powered by an unspecified diesel engine, but sometime during the development stage, this was dropped in favor of a petrol engine. The main engine chosen was a 450 hp 19.814-liter air-cooled Škoda V12 running at 3,500 rpm. Interestingly, a second small auxiliary engine producing just 50 hp was also planned to be added. The purpose of this small auxiliary engine was to power up the main engine and provide extra power. While the main engine was started by using the auxiliary engine, this one, in turn, would be started either electrically or by using a crank. The maximum theoretical speed was around 58-60 km/h.
The T-25 was influenced by the Soviet T-34. This is most apparent in the sloping armor design. The T-25 would be built by using welded armor on both the superstructure and the turret. The armor design seems to have been a very simple design, with angled armor plates (of which the exact angle is unknown but was possibly in the range of 40° to 60°). This way, the need for more carefully machined armored plates (like on Panzer III or IV) was unnecessary. Also, by using larger one-piece metal plates, the structure was made much stronger and also easier for production.
The armor thickness was in the range of 20 to 50 mm according to official factory archives, but according to some sources (such as P.Pilař), the maximum front armor was up to 60 mm thick. The maximum thickness of the frontal turret armor was 50 mm, the sides were 35 mm, and the rear between 25 to 35 mm thick. Most of the turret armor was sloped, which added extra protection. The hull upper front plate armor was 50 mm, while the lower was also 50 mm. The side sloped armor was 35 mm while the lower vertical armor was 50 mm thick. The roof and floor armor were the same 20 mm thickness. The T-25 dimensions were 7.77 m long, 2.75 m wide, and 2.78 m high.
The hull design was more or less conventional with a separated frontal crew compartment and the engine in the rear, which was divided from the other compartments by an 8 mm thick armored plate. This was done in order to protect the crew from engine heat and noise. It was also important to protect them from any possible outbreaks of fire arising because of some malfunction or combat damage. The total weight was calculated to be around 23 tonnes.

Crew

The T-25 crew consisted of four members, which may seem strange by German standards, but the use of an automatic loading system meant that the lack of a loader was not a problem. The radio operator and the driver were located in the vehicle hull, while the commander and the gunner were in the turret. The front crew compartment consisted of two seats: one on the left for the driver and the second to the right for the radio operator. The radio equipment used would most likely have been a German type (possibly a Fu 2 and Fu 5). The forward mounted turret design on the T-25 had one significant issue in that the crew members in the hull had no hatches at either the hull top or sides. These two crew members had to enter their battle positions through the turret hatches. In case of an emergency, where crew members had to make a quick escape from the vehicle, it could take too much time or would perhaps be impossible because of combat damage. According to T-25 drawings, there were four viewports in the hull: two on the front and one on both of the angled sides. The driver’s armored viewports appear to be the same design (possibly with armored glass behind) as on the German Panzer IV.
Located in the turret was the rest of the crew. The commander was located at the left rear of the turret with the gunner in front of him. For observation of the surroundings, the commander had a small cupola with a fully rotating periscope. It is unknown if there would have been side viewports on the turret. There is a single hatch door for the commander in the turret, possibly with one more on top and perhaps even one to the rear as with the later Panther design. The turret could be rotated by using a hydroelectric or mechanical drive. For communication between the crew, especially the commander and the hull crew members, light signals and a telephone device were to be provided.


Illustration of the T-25 with the earlier turret design.


Illustration of the T-25 with the second design turret. This is how the T-25 would probably have looked if it went into production.

3D model of the T-25. This model and the above illustrations were produced by Mr. Heisey, funded by our Patron DeadlyDilemma through our Patreon campaign.

Armament

The main weapon chosen for the T-25 was interesting in many ways. It was Škoda’s own experimental design, a 7.5 cm A18 L/55 caliber gun with no muzzle brake. In Germany, this gun was designated as 7.5 cm Kw.K. (KwK or KwK 42/1 depending on the source). The gun mantlet was rounded, which offered good ballistic protection. This gun had an automatic drum loading mechanism containing five rounds with a maximum estimated rate of fire of around 15 rounds per minute, or around 40 rounds per minute at full auto. The gun was designed so that, after firing each round, the spent case would be automatically ejected by compressed air. The A18 muzzle velocity was 900 m/s according to official factory archives. Armor penetration at a range of 1 km was around 98 mm. The T-25 ammo capacity was to be around 60 rounds; most would be AP with a smaller number of HE rounds. The total gun (together with mantlet) weight was around 1,600 kg. The A18 gun elevation was -10 to +20°. This gun was actually constructed during the war but because of the cancellation of the entire project, it was probably put into storage, where it remained until the war ended. After the war research continued and it was tested on one Panzer VI Tiger I heavy tank.
The secondary weapon was a light machine gun of unknown type (with an estimated 3,000 rounds of ammunition) located on the right front side of the turret. Whether it was coaxially mounted with the main gun or used independently (as on Panzer 35 and 38(t)) is unknown, but the former is most probably correct as it is more practical and was in general use on all German tanks. It is unknown if there was a hull ball-mounted machine gun, although the few existing illustrations do not appear to show one. It is possible that it would be installed and in that case, it would be operated by the radio operator. It is equally possible that the radio operator would use his personal weapon (possibly MP 38/40 or even MG 34) to fire through his front viewport similar to the later Panther Ausf. D’s MG 34 ‘letterbox’ flap. Regardless, the possible absence of a hull machine gun was not a significant defect, as it results in weak spots on the frontal armor. If the T-25 did use a hull machine gun (and in the turret), it would likely have been either the standard German MG 34 that was used in all German tanks and vehicles in both coaxial and hull mounts or the Czechoslovakian VZ37 (ZB37). Both were 7.92 mm caliber machine guns and used by the German until the end of War War Two.

Modifications

Similar to other German armored vehicles, the T-25 tank chassis was to be used for different self-propelled designs. Two similar designs with different guns were proposed. The first was to be armed with a lightweight 10.5 cm howitzer.

This is possibly the only wooden mock-up of the Škoda proposed self-propelled designs based on the T-25. Photo: SOURCE
There is confusion as to which exact howitzer was used. It could have been the Škoda-built 10.5 cm leFH 43 howitzer (10.5 cm leichte FeldHaubitze 43), or the Krupp howitzer of the same name. Krupp built only a wooden mock-up while Škoda built a functional prototype. We must also consider the fact that as the T-25 was a Škoda design it would be logical to assume that the designers would use their gun instead of the Krupp one. The Škoda 10.5 cm leFH 43 howitzer was designed from late 1943 and the first operational prototype was built only by the war’s end in 1945.
The 10.5 cm le FH 43 was an improvement of the existing leFH 18/40 howitzer. It had a longer gun but the biggest innovation was the design of the carriage which allowed a full 360° of traverse. The 10.5 cm leFH 43 characteristics were: elevation -5° to + 75°, traverse 360°, weight in action 2,200 kg (on a field carriage).

The Škoda 10.5 cm leFH 43 howitzer. Photo: SOURCE
However, there is a considerable chance that the gun that would, in fact, be used was the 10.5 cm leFH 42. This gun was designed and built in limited numbers around the same time (in 1942) as the T-25. Both Krupp and Škoda howitzers were designed and built long after the T-25 was developed. The 10.5 cm le FH 42 muzzle brake is very similar to the wooden mock-up, but this is not a definitive proof that this was the weapon, merely a simple observation.
The 10.5 cm leFH 42 characteristics were: elevation -5° to + 45°, traverse 70°, weight in action 1,630 kg (on a field carriage), maximum range up to 13,000 km with velocity of 595 m/s. The 10.5 cm le FH 42 was rejected by the German army and only a few prototypes were ever built.

One of the few 10.5 cm Le FH 42 ever built. Photo: SOURCE
There is a real chance that none of these two howitzers would have been used if this modification had entered production. The reasons for this are the following: 1) none of the three 10.5 cm howitzers were available as they had either not been accepted for service by the German army or were not ready by the end of war 2) Only the wooden mock-up was built of the 10.5 cm self-propelled vehicle based on the T-25. The final decision for the main weapon would have been made only after an operational prototype was constructed and adequately tested. As it was only a paper project we can not know with certainty whether the modification itself was feasible in practice 3) due to ease of maintenance, ammunition and the availability of spare parts the in-production 10.5 cm leFH 18 (or later improved models) would have been the most likely candidate.
The second proposed design was to be armed with a more powerful 15 cm sFH 43 (schwere FeldHaubitze) howitzer. Several artillery manufacturers were asked by the German army to design a howitzer with all-around traverse, a range of up to 18,000 km, and a high elevation of fire. Three different manufacturers (Škoda, Krupp, and Rheinmetall-Borsig) responded to this request. It would not go into production as only a wooden mock-up was ever built.
Only a wooden mock-up of the vehicle armed with the 10.5 cm seems to have been made due to the cancellation of the T-25 tank. Beside the main guns that are to be used, nothing much is known about these modifications. According to the old photograph of the wooden model, it looks like it would have had a fully (or at least partially) rotating turret with a light machine gun. On the hull side, we can see what looks like a lifting crane (possibly one on both sides), designed to dismount the turret. The dismounted turret may then have been used as static fire support or placed on wheels as ordinary towed artillery, similar to the 10.5cm leFH 18/6 auf Waffentrager IVb German prototype vehicle. On the top of the engine compartment, some extra equipment (or parts of the gun) can be seen. On the vehicle rear (behind the engine) there is a box that looks like a holder for wheels or possibly for extra ammunition and spare parts.

Rejection

The story of the T-25 was a very short one and it did not progress beyond blueprints. Despite the hard work of Škoda workers, nothing besides plans, calculations, and wooden models was ever made. The begs the question: why was it rejected? Unfortunately, due to the lack of adequate documentation, we only can speculate as to the reasons. The most obvious is the introduction of the better armed Panzer IV Ausf. F2 model (armed with longer 7.5 cm gun) which could be built using existing production capacity. The first fully operational T-25 would probably only be able to have been built in late 1943, as the time needed for testing and adopting it for the production would have taken too long.
By late 1943, it is questionable whether the T-25 still would be a good design, it may possibly already be considered obsolete by that point. Another possible reason for rejection was the reluctance of the German army to introduce yet another design (as at that time Tiger development was underway) and thus put more stress on the already overburdened war industry. It is also possible that the Germans were not willing to adopt a foreign design and instead favored domestic projects. Another reason may be the experimental gun itself; it was innovative but how it would perform in real combat conditions and how easy or complicated it would be for production is uncertain at best. The need for the production of new ammunition would also complicate the already over-complicated German ammunition production. So it is understandable why the Germans never accepted this project.
In the end, the T-25 was never adopted for service even though (at least on paper), it had a good gun and good mobility, solid armor, and a relatively simple construction. It should be borne in mind, however, that this was a paper project only and that in reality may be the results would have been completely different. Regardless, due to its short development life after the war, it was mostly forgotten until relatively recently, thanks to its appearance in online games.

Specifications

Dimensions (L-W-H) 7.77 x 2.75 x 2.78 m
Total weight, battle ready 23 tonnes
Crew 4 (gunner, radio operator, driver and commander)
Armament 7.5 cm Škoda A-18
unknown light machine-guns
Armor 20 – 50 mm
Propulsion Škoda 450 hp V-12 air-cooled
Speed on /off road 60 km/h
Total production None

Source

This article has been sponsored by our Patron DeadlyDilemma through our Patreon campaign.
The author of this text would take the opportunity to express special thanks to Frantisek ‘SilentStalker’ Rozkot for helping with writing this article.
Projekty středních tanků Škoda T-24 a T-25, P.Pilař, HPM, 2004
Enzyklopadie Deutscher waffen 1939-1945 Handwaffen, Artilleries, Beutewaffen, Sonderwaffen, Peter Chamberlain and Terry Gander
German Artillery of World War Two, Ian V.Hogg,
Czechoslovak armored fighting vehicles 1918-1945, H.C.Doyle and C.K.Kliment, Argus Books Ltd. 1979.
Škoda T-25 factory design requirements and drawings, dated 2.10.1942, document designation Am189 Sp
warspot.ru
forum.valka.cz
en.valka.cz
ftr-wot.blogspot.com
ftr.wot-news.com

Categories
WW2 Czechoslovak Prototypes

Kolohousenka

Czechoslovakia Czechoslovakia (1923-1930)
Artillery tractor and tank – 5 built

When the Czechoslovak army bought their first tanks in the early twenties, seven French Renault FTs, they already wanted to produce tanks in their own country. Combined with an interest in the so-called wheel-cum-track tanks, they bought the rights in 1923 to produce an agricultural tractor, modified by German tank designer Joseph Vollmer. This tractor, called WD Z 50PS, was originally produced at the Hanomag company in Hanover, Germany. Although this Czechoslovak project started as an artillery tractor, it ended up being the first tank built in Czechoslovakia

This is the original converted Hanomag tractor by Vollmer, on which the vehicles were based. On the Kolohousenka vehicles, the engine was moved to the back. Photo: warspot.ru

The Idea of Wheel-Cum-Track

Some of the main shortcomings of early tanks were their slow speed and the short life of the tracks. One solution for these problems was designed by famous American tank designer Walter Christie. Christie’s design had removable tracks so the tank could drive on its wheels. This solution is best known for its use on the Soviet BT tank series.
Another wheel-cum-track solution was more sophisticated. This solution consisted of a four-wheeled chassis merged with a tracked chassis. The wheels could be lowered or lifted and be fixed in the needed position, so the tank could either drive on its wheels or tracks. This system combined fast speed on roads with good terrain resistance, but it was very complex, resulting in difficulties in building and repairing, which led to high production costs.
Due to the positive aspects of this system, it gained wide interest in multiple countries, including Britain and Sweden. Several experimental vehicles were developed, like the Swedish Landsverk L-5 and the British Vickers D3E1, but the negative aspects meant that most projects remained in their experimental stage, including the Kolohousenka project.

Good sideview of the KH-50 tank. Note the ramps on the side and the unfolded front hatch. Photo: warspot.ru

Development

After the introduction of tracked vehicles in World War I, caterpillar-tracked vehicles also gained interest in the agricultural department of the German company Hanomag. Two of their designers, Ernst Wendeler and Boguslav Dohrn, started designing tracked tractors and came up, among others, with the WD Z 25 in 1920 and the WD Z 50 in 1921. Both of these vehicles gained interest from the Czechoslovak army and they bought respectively two of the former and four of the latter between 1923 and 1927. The rights to produce both tractors locally were also bought.
At the same time, Joseph Vollmer, who had designed tanks in World War I, designed his own wheel-cum-track system, based upon the WD Z 50. In 1923, the Ministry of Defense (Ministerstvo národní obrany or MNO) bought the documentation on his design for a total of Kč1.3 million (the equivalent of approximately US$516.750 in 2017 values). After evaluation of the design, it was thought to be suitable and the company Breitfeld-Daněk (which would later merge into Českomoravská-Kolben-Daněk) was ordered to build two experimental vehicles. Note that these vehicles were intended as artillery tractors. They also asked the companies Ringhoffer (later Tatra) and Laurin & Klement (later Škoda) to assist in the development and building process. In 1924, the first two vehicles were ready and given the designation KH-50. 50 referred to the horsepower rating of the engine and KH was the abbreviation of Kolohousenka, the merging of the Czech words ‘kolo’ and ‘housenka’, meaning ‘wheel’ and ‘caterpillar’ respectively.
These two tractors were tested in the city of Prague by the Military Technical Institute (Vojenský Technický Útvar or VTU). One of the two vehicles broke down in a very short time and was in such a bad state that it had to be scrapped. The other tractor was modified and an armored superstructure was added, together with a fully rotating turret mounting a 37mm gun. With this armored addition, the vehicle became the first Czech-built tank. Tests continued with the tank, but the army was not convinced that this tank would be a worthy acquisition and no order was placed.
In 1927, the leading company in the design, Breitfeld-Daněk, merged with the company Českomoravská-Kolben and formed CKD. This lead not to the termination of the project, instead it was decided to modify the vehicle again. The complete vehicle was revised and the engine was replaced by a more powerful WD 60PS 60hp engine. The turret was also replaced, by a round-shaped one which carried two machine guns. The designation of this modified vehicle as it now had a 60hp engine was changed to KH-60. Despite the improved performance, the army still decided not to order it, but they accepted the prototype in 1930 and it received the registration number 13362. Two more vehicles were built as tractors, which got the attention of the Soviet Union and both were sold to them in 1927. The Soviets already had the Kommunar tractors in service, which were also based on the WD 50 tractor.

The KH-50 tank showing how the ramps are used to change from tracks to wheels. Photo: Bellona Publishing
After two years, in 1929, CKD made its last attempt to improve the vehicle and sign a contract with the army. The turret was rebuilt and the lifting system of the wheels was improved and made more reliable. The engine was replaced, again by a more powerful one, with 70hp. The designation for this vehicle was now KH-70. However, the Czech army was not interested at all in buying the vehicle, because they viewed it as obsolete. The vehicle was examined by the Italian army, but if it was sold to them is unclear. Due to the failure of this latest creation, the project was finally canceled and CKD turned its attention to building ‘normal’ tanks.

Specifications

Dimensions (L-W-H) 4.5 x 2.39 x 2.53m (14.8 x 7.8 x 8.3 ft)
Total weight, battle ready 7.5-10 tons
Crew 2 (commander, driver)
Propulsion Hanomag WD 50PS, 50 hp
Speed 21.7 mph (35 kph) on wheels, 9.3 mph (15 kph) on tracks (both on road)
Range 186 miles (300) km on wheels on road
Armament 3.7 cm Škoda infantry gun
Armor 6 – 14 mm (0.24 – 0.55 in)
Total production 5

Links, Resources & Further Reading

-Czechoslovak armoured fighting vehicles 1918-1945, Bellona Publishing, by Charles K. Kliment and Hilary Louis Doyle, 1979.
-V.Francev, Ch.K.Kliment “Československa obrnena vozidla 1918-48”. Prague. 2004
-Czechoslovak heavy armored vehicles. Development, production, operational use and export of the Czechoslovak tanks, armored cars and tracked artillery tractors 1918-1956, PhDr. Ivo Pejčoch, Karlova University, Prague, 2009
docplayer.cz
www.delostrelectvocsarmady1918-1939.estranky.cz
www.trekkermuseum-otmmz.nl
utocnavozba.wz.cz


The KH-50 light tank prototype. Note the Renault FT-like turret and the tow hook at the back, possibly a remain from the original tractor.

The KH-60 had a redesigned front, a new more powerful engine and a new cylindrical turret.

The last of the series, the KH-70 had an even more powerful engine and a conical type turret with a mushroom-type cupola. Also note the tail added to the vehicle, meant to aid crossing trenches.
All illustrations done by Bernard “Escodrion” Baker. These illustrations have been sponsored by Golum through our Patreon page.

Design

The engineer who participated in the design process of this vehicle and became very successful was the Russian engineer Alexey Surin. He fled to Czechoslovakia after the Reds had won the civil war and became an engineer of CKD in 1923.
The KH-50 used the original engine, a Hanomag four-cylinder, four-stroke, water cooled 50 hp engine, but it was swapped from the front to the back of the tractor. It could be powered with either benzene, gasoline or kerosene. The KH-60 and KH-70 were both powered by more powerful engines from the same company. The driver’s position was moved from the back to the front and lowered into the hull. The front hull was redesigned and somewhat similar to the Renault FT, already in use in the Czechoslovak army.

Picture of the KH-60 tank. The main layout differences are quite good visible. The exhaustion is moved to the top of the tank and the front has been redesigned, as well as the turret. Photo: utocnavozba.wz.cz
When the first vehicle was rebuilt as a tank, the superstructure and turret were designed and built by Škoda. It consisted of riveted flat sheets of armor, and the design was inspired by the Renault FT, especially noticeable in the front armor and turret. In this turret, a 3.7cm Škoda d/27 gun was mounted. When the vehicle was rebuilt as KH-60, the turret was changed to a cylindrically shaped one, designed by CKD. This turret mounted two 7.92mm Schwarzlose vz.24 machine guns. A 47mm Vickers was also considered. A rear tail was added to the KH-70 model to improve trench crossing.
Changing from wheel to track had to be done manually by the crew. This took about fifteen minutes. The ramps to change were carried on the sides of the vehicle. With the KH-70, the time to change was reduced to ten minutes. The crew consisted out of two men, a driver, and a commander. The driver was located in front of the tank, while the commander was located in the turret and also acted as loader and gunner, the same situation as in the Renault FT. The commander could get inside via hatches installed on both sides of the vehicle. The driver could get in through hatches mounted in the front of the vehicle, again comparable to the FT.

The KH-70 tank. Only one vehicle of this type was made. Either the turret is turned, or the armament is not installed. Photo: Aviarmor.net
A distinctive feature of the vehicle were the two headlights, which were mounted on the hull. On the KH-50 tank model, they were built into the hull, resulting in two ball-like extensions. The exhaust pipe was located at the side but was moved to the top of the vehicle with the KH-60 and 70. None of the three models had a radio installed, so communication had to be performed with hand signals or flags. The engine could be reached by one hatch, covering the complete back of the vehicle, and two smaller hatches at the sides. The armor on the turret and the front was 14mm thick.

Fate

As already mentioned in the development section, one of the first two KH-50’s tractors was scrapped due to a bad break down. The other vehicle was modified as a tank and later on remodeled into the KH-60, was bought by the army and examined until 1935, when the vehicle was installed as a static monument in front of the Tank School. Although it was effectively taken out of service, it was still mentioned in German handbooks in 1939. After the German invasion of Czechoslovakia, it was taken to a German depot where it was scrapped.
It is not known what happened with the two artillery tractors delivered to the Soviet Union. No photographs are known of the vehicles in Soviet service and their fate is also unknown, as is the case with the KH-70. With the experience gained by this project, Tatra designed a wheel-cum-track tractor on their own in 1929, the Tatra KTT, but the army was not interested in this project either.
After the cancellation of the project in 1930, interest in wheel-cum-track vehicles wained, but research was still being done by both Škoda and Tatra. They received orders in 1929 to design a heavy wheel-cum-track tank and they came up with respectively the Š-III and T-III. Vollmer’s design was not allowed to be used anymore because its building rights had expired and had to be bought again if they wanted to use it. Instead, the companies had to come up with their own design. Each company built two prototypes, but they suffered from severe technical malfunctions. Like the Kolohousenka, these vehicles were a failure, and the army abandoned the idea of a wheel-cum-track vehicle for good.
Originally published on February 17, 2018

Categories
WW2 Czechoslovak Prototypes

Libenska-ČKD F-IV-H

Czechoslovakia (1936-43)
Amphibious Light Tank – 2 Prototypes Built

In 1933, ČKD (Českomoravská Kolben-Daněk) built the Tančik vz. 33 (P-I), however they were not pleased with the design and started a project on their own which would become the LT vz.34 (P-II) light tank of which fifty were made. These P numbers of the vehicles designated the type of tank. I stood for tankette where II stood for Light tank, however this second category got split up into IIa and IIb in 1934, respectively standing for cavalry tank and infantry tank, so ČKD started designing and came up with the P-IIa and P-IIb in 1936

First prototype outside factory. Photo: rotanazdar.cz

Development

In October 1936, both Škoda and ČKD received orders from the Czechoslovakian Army and the VTLÚ (Vojenský technický a letecký útvar or Military Technical and Aerospace Institute) to develop the first Czechoslovakian amphibious tank. During the same year, ČKD started development and on January 29th, 1937, they delivered two alternative designs to the MNO (Ministry of Defence) which were based upon the already developed P-IIa and b tanks. With no previous amphibious tank design experience and a lack of available foreign assistance, the design process proved difficult. Engineers in Great Britain and the Soviet Union had experience with amphibious designs, but due to a deteriorated relationship with the Soviet Union, caused by the armed conflict between the Bolsheviks and Czechoslovak Legions, and a negative view of British amphibious tank designs, neither were asked to assist.
On April 28, 1937, the commander of the VTLÚ, Ing. Dr. František Kolařík wrote in a report to the MNO: “The amphibious tanks designed by the two companies are based on experience gained in manufacturing and testing light tanks, tracked tractors as well as various river vessels. Regarding the overall concept of the amphibious tanks designed by ČKD, they are both respectively based on the P-IIa and P-IIb prototype tanks, with the exception of the engine and the way the drive and gear assembly are designed. (…) The disadvantage of all projects is the need to have very tightly strung tracks when driving on ground, resulting in a considerable loss of engine power during movements and little ability to adapt to unevenness. The hull is designed with sufficient buoyancy for swimming. Each project has two propellers, which are driven by the drive axle by the ČKD projects, but the Škoda project uses a special transfer directly from the engine. Changes in direction should be performed by disengaging the drive or reducing the speed of one or the other propeller, according to ČKD, or, according to Škoda, by disengaging the propulsion of one or the other bolt or the counter-flow of one of the propellers. The ČKD project is assessed to be better suited because its whole unit is mounted at the rear of the vehicle and completely separate from the combat compartment.
After considering both proposals, the VTLÚ recommended that prototypes should be ordered from both companies, because of the difficult production of amphibious tanks and lack of experience building them. Because ČKD handed in two proposals, a choice had to be made. After comparisons, the second proposal was chosen as it had more favorable characteristics. On November 12, 1937, the MNO ordered the construction of a prototype for the price of 718.000 CZK (nowadays around $350,000). In the order, it was also stated that the prototype had to be delivered before August 12, 1938.
Work on the prototype ran until the spring of 1938. The first reports appeared on April 26 when 16 technical drawings of the vehicle were realized. The number of schematics became bigger and bigger with 47 drawings on June 30 and already a total of 262 drawings on August 6. On August 20, work on the details began and by September 13, a total of 401 schematics had been produced. The deadline was extended by the MNO to 12 October, giving two months extra time.
On October 19, the deadline was again extended to the end of the year. Two liquidation orders were proposed if the tank eventually could not be delivered. Firstly, at least a part of the tests had to be paid either by the company or the military administration. Secondly, if any tanks would be sold abroad, a percentage fee of the price would be requested for intellectual property by the government. At the start of the next month, a report came in from Libeňská Engineering that a total of 415 drawings had been made and work on all the details in the mechanical workshops progressed quickly.
By November 17, the deadline was extended again until January 12, 1939. Four days later, a conference was held at the Ministry of National Defence about the amphibious tanks. The attendants came to the conclusion that the programme shouldn’t be stopped and negotiations had to continue. The percentage fee of intellectual property had to be determined after receiving and testing the vehicles from both Škoda and ČKD, due to delivery delays.
One month later, on the 7th of December, the first engine tests were launched with both alcohol-petrol mixtures and ‘dynalkolem’, a mixture of 50% fermented alcohol, 30% benzene, and 20% gasoline. After about 4 hours, a problem occurred with the electric brake, but six days later everything worked as it was supposed to and the tests were successfully completed.
Next year, on January 25, Libeňská Engineering reported that the vehicle was working. Some months later, in April, it was announced that the vehicle was in running condition and had been tested by the factory in the river Moldau in Prague, but wasn’t officially been tested by the military. Meanwhile, work was still being done on an observation device. After the German annexation of Czechoslovakia in March 1939, work continued on the project and the German military also showed interest in the project.
From 2 to 6 May 1939, representatives of the company, which was renamed Böhmisch-Mährische Maschinenfabrik AG (BMM AG), had negotiations with the German Heereswaffenamt or German Weapons Agency. The German committee consisted of Oberstleutnant Fichtner, Dr. Olbricht, Major Tomala, Oberst Reg. Baurat Beier en Oberst Reg. Baurat Mosel. During these negotiations, it became clear that the F-IV-H wasn’t ripe for serial production and further internal testing at the factory had to take place. This request was approved, but the test results had to be sent to the German WaPrüf 6. WaPrüf is the abbreviation from ‘Waffenprüfamt’or ‘Weapons testing office’. Several of these offices formed the Heereswaffenamt. BMM AG tried to offer the F-IV-H abroad, but the German military administration blocked this and marked the project as secret.
On May 23, the Czech “Ministry of National Defense in Liquidation” extended the delivery time to 31 July. Within delivery time, on June 22, the National Engineering Research and Testing Institute, the former VTLÚ, was informed that the prototype was ready for testing. The formal reply suggested that the company should notify the German army. They indeed showed further interest and on November 2, a second prototype was ordered, which bore the name F-IV-H/II. The factory was visited by Mr. Keiling on behalf of WaPrüf 6 a month later. He promised that the prototype could remain for demonstration purposes. During the same month, the company received permission to offer the F-IV-H abroad, however, the vehicle wasn’t ordered either by the Germans or foreign countries and further development was canceled.
Meanwhile, the Škoda ŠOT had also been built and tested, but it was reportedly too heavy and could barely maneuver in the water. It is not known when the first ČKD prototype was scrapped. The second prototype was sent to Kummersdorf, where it was tested. The last trace of this vehicle was found in early 1943 when new tracks and pins were ordered, but by this time, further development had already been canceled.

First prototype without floatation skirts. Photo: rotanazdar.cz


Illustration of the ČKD F-IV-H by Tank Encyclopedia’s own Jarosław Janas

Design

Initially, ČKD came up with two alternative designs. The first design was propelled by a conventional six-cylinder water-cooled engine, with an output of 95 hp at 2000 rpm. The second design was propelled by a four-cylinder water-cooled engine with an output of 100 hp at 2000 rpm. Both alternatives had an vertical exhaust pipe, which would limit the turret traverse. The second alternative was chosen.
The crew consisted of three people; The commander/gunner, driver and a radio-operator. The driver was located in the right front of the tank and had a sight with bulletproof glass. The radio-operator sat to his left and the commander was located in the turret.

F-IV-H front interior. The driver sat to the right and the radio-operator to the left. Photo: rotanazdar.cz
The chassis was a heavily modified version of one used by the famous LT vz. 35 tank. Power was distributed through a Praga-Wilson gearbox with four road wheels and two return rollers on each side. The engine was a Praga F4 water-cooled 4-cylinder producing 120 hp at 2200 rpm. Two propellers were mounted at the rear of the vehicle and connected to the drive axle. The armament consisted of only a 7.92 mm ZB-37 machine gun, located in the turret. Frontal armour was 14 mm thick and the top and bottom armor plates were 7 mm thick.
The differences between F-IV-H prototype I and II were minor, with the II having a slightly modified turret, a lifted cupola, a better cooling system, a redesigned floating system and a new exhaust system.

Export

At the end of 1939, offers were sent to Sweden, Persia and the Netherlands. The export model received the designation F-IV-HE and was described as a fast and easily manageable combat vehicle. The armor could withstand bullet fire, even at a distance of 100-150 meters. It was suitable for both terrain or water maneuvers. The factory also stated in the offers that 20 to 25 units could be delivered per month within a maximum time span of five months.
Of the three contacted countries, only the Persian War Ministry and General Staff showed interest. In April 1940, a technical description with additional photographs was sent and further communication took place via Berlin. It was assumed that Persia would buy around 200 vehicles, including a few F-IV-H vehicles. In the end, Persia ordered only twenty vehicles and this order didn’t contain the F-IV-H. It is possible that this is due to a lack of interest of the Persian War Department, but it’s more likely a result of a restriction from the German department. Later on, a new offer was sent to Argentina, but they showed no interest either.

Conclusion

Despite the efforts of the engineers, the F-IV-H was not a successful project. The Czech army was skeptical about it because of the long delivery period and when it was tested, it did not perform as planned. Although the German continuation of the project the vehicle was still not suitable for combat and in the early stage of the war already outdated. Both prototypes were scrapped during the war.

The F-IV-H second prototype. Photo: rotanazdar.cz

ČKD F-IV-H specifications

Dimensions (L-W-H) 4.85 x 2.5 x 2.08 m (15.9 x 8.2 x 6.8 ft)
Total weight, battle ready 6.5 t (14,330 lbs)
Crew 3 (commander, driver, radio operator)
Propulsion Praga F-IV, 4-cylinder, 120 hp
Speed 45 kph / 28 mph – road, 6 kph / 3,7 mph – water
Range 200 km / 125 mi
Armament ZB vz. 37 7.92mm machinegun.
Armor 7-14 mm / 0.28 – 0.55 inches
Total production 2 Prototypes

Links, Resources & Further Reading

Czechoslovak armoured fighting vehicles 1918-1945, H.C. Doyle, C.K. Kliment
On Aviarmor.net
On tanksinworldwar2.com
On utocnavozba.wz.cz
On rotanazdar.cz
Google maps view of where the water testing took place, libeňský zámeček (libeňský mansion) HERE